pub(crate) fn compute(data: &[u8]) -> [u8; 32] {
let mut h: [u32; 8] = [
0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab,
0x5be0cd19,
];
let bit_len = (data.len() as u64) * 8;
let mut padded = data.to_vec();
padded.push(0x80);
while padded.len() % 64 != 56 {
padded.push(0);
}
padded.extend_from_slice(&bit_len.to_be_bytes());
for chunk in padded.chunks_exact(64) {
let mut w = [0u32; 64];
for (i, word) in chunk.chunks_exact(4).enumerate() {
w[i] = u32::from_be_bytes([word[0], word[1], word[2], word[3]]);
}
for i in 16..64 {
let s0 = w[i - 15].rotate_right(7) ^ w[i - 15].rotate_right(18) ^ (w[i - 15] >> 3);
let s1 = w[i - 2].rotate_right(17) ^ w[i - 2].rotate_right(19) ^ (w[i - 2] >> 10);
w[i] = w[i - 16]
.wrapping_add(s0)
.wrapping_add(w[i - 7])
.wrapping_add(s1);
}
round(&mut h, &w);
}
let mut result = [0u8; 32];
for (i, &word) in h.iter().enumerate() {
result[i * 4..i * 4 + 4].copy_from_slice(&word.to_be_bytes());
}
result
}
fn round(state: &mut [u32; 8], w: &[u32; 64]) {
const K: [u32; 64] = [
0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4,
0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe,
0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f,
0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc,
0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116,
0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7,
0xc67178f2,
];
let (mut a, mut b, mut c, mut d, mut e, mut f, mut g, mut hh) = (
state[0], state[1], state[2], state[3], state[4], state[5], state[6], state[7],
);
for i in 0..64 {
let s1 = e.rotate_right(6) ^ e.rotate_right(11) ^ e.rotate_right(25);
let ch = (e & f) ^ ((!e) & g);
let temp1 = hh
.wrapping_add(s1)
.wrapping_add(ch)
.wrapping_add(K[i])
.wrapping_add(w[i]);
let s0 = a.rotate_right(2) ^ a.rotate_right(13) ^ a.rotate_right(22);
let maj = (a & b) ^ (a & c) ^ (b & c);
let temp2 = s0.wrapping_add(maj);
hh = g;
g = f;
f = e;
e = d.wrapping_add(temp1);
d = c;
c = b;
b = a;
a = temp1.wrapping_add(temp2);
}
state[0] = state[0].wrapping_add(a);
state[1] = state[1].wrapping_add(b);
state[2] = state[2].wrapping_add(c);
state[3] = state[3].wrapping_add(d);
state[4] = state[4].wrapping_add(e);
state[5] = state[5].wrapping_add(f);
state[6] = state[6].wrapping_add(g);
state[7] = state[7].wrapping_add(hh);
}
#[cfg(test)]
mod tests {
use super::*;
fn hex(bytes: &[u8]) -> String {
use std::fmt::Write as _;
let mut out = String::with_capacity(bytes.len() * 2);
for byte in bytes {
let _ = write!(out, "{byte:02x}");
}
out
}
#[test]
fn sha256_test_vectors() {
assert_eq!(
hex(&compute(b"")),
"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
);
assert_eq!(
hex(&compute(b"abc")),
"ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
);
}
}